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Face Nerve Paralysis in Dogs

Facial Nerve Paresis/Paralysis in Dogs

Facial nerveparesis is a dysfunction of the seventh cranial nerve, the facial nerve. This condition is evidenced by paralysis or weakness of the muscles of the ears, eyelids, lips, and nostrils.

The cause of this disease is impairment of the facial nerve, or of the place where the nerves come together, and it affects the electrical impulses of the nerves involved. The facial nerve is affected, and sometimes the ophthalmic system as well, interfering with the function of the tear glands. Dry eye syndrome also accompanies the tear gland interference. Gender does not play a role, but breed appears to in some cases. Adult age Cocker Spaniels, Pembroke Welsh corgis, boxers, and English setters are most likely to experience this condition.

Symptoms and Types

Messy eating; food left around mouth

Food falling from the side of the mouth

Excessive drooling

Inability to close eye; rubbing; discharge from eye

Inability to close the eyelids

Wide separation between the upper and lower eyelids

Decreased or absent menace response and eyelid reflex

Facial asymmetry

Ear and lip drooping

Collapse of the nostril

Chronic - patient may have deviation of the face toward the affected side

Occasional facial spasms may be observed

Discharge of pus from the affected eye

Somnolence or stupor

Causes

One sided facial nerve paresis:

Idiopathic (unknown cause)

Metabolic - hypothyroid

Inflammatory - otitis media-interna: inflammation of the inner ear

Nasopharyngeal polyps: benign growths that can occur in the back of the throat, the middle ear and even perforate through the ear drum – rare in dogs

Cancer

Trauma - fracture of a bone at the base of the skull; injury to the facial nerve

Diagnosis

You will need to give a thorough history of your dog's health, onset of symptoms, and possible incidents that might have preceded this condition.

Your veterinarian will first determine whether the paresis is one sided or both sided, and will then look for other neurological signs. Unless your dog has had an ear disease, or other neurological deficits, the cause will be determined as unknown. Some of the causes that will be considered will be possible middle or inner ear disease; if your dog is lethargic and has a poor hair coat, a test for hypothyroidism will be done; if your dog is sleeping a lot and is displaying symptoms related to a brainstem disorder, a disease of the central nervous system will be considered.

A complete blood profile will be conducted, including a chemical blood profile, a complete blood count, and a urinalysis, although these are typically normal in the case of facial paralysis. Even so, there are some disorders that might account for the symptoms, such as an anemia, excessive production of cholesterol, or low blood sugar.

X-rays, computed tomography (CT) scans, or magnetic resonance imaging (MRI) may be used to detect the location of the problem. There are also other tests that can be used to evaluate tear production, motor nerve conduction speed, and for the detection of brainstem disease.